Probing high-pressure reactions in heterogeneous materials by Raman spectroscopy

The characterization of pressure induced structural and chemical transformations employing the Diamond Anvil Cell (DAC) technique often requires a high spatial resolution. This is due to the small sample dimensions when the compression reaches the megabar range, or when heterogeneous materials are obtained in pressure induced chemical reactions. The characterization of these samples can be performed by using synchrotron light based techniques, which can provide optical or X-ray spots of few microns, whereas laboratory experiments are limited to Raman spectroscopy. Here we describe a cutting-edge Raman system with a transverse spatial resolution of 1-3 ?m dedicated to the characterization of samples compressed in DACs. A few examples of the application of this technique to characterize different heterogeneous materials before and after high-pressure chemical reactions are reported to enlighten the performances of the system